Carburetor supplemental fuel supply

Abstract

A carburetor provides a supplemental fuel supply to an engine and includes a body, a fuel metering diaphragm and a fluid pump. The fuel metering diaphragm defines part of a fuel metering chamber and a reference chamber and has at least a portion that is movable relative to the body to increase and decrease the volume of the fuel metering chamber to control fuel flow in the fuel metering chamber. The fluid pump is carried by the carburetor or another component upstream of the carburetor and has an outlet in fluid communication with the metering reference chamber and an actuator arranged to discharge fluid through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage to provide a supplemental fuel supply to the engine.

The invention claimed is: 
     
       1. A carburetor that provides a supplemental fuel supply to an engine, comprising:
 a body having an air-fuel passage from which a fuel and air mixture flows from the carburetor, and a fuel metering chamber from which fuel flows to the air-fuel passage; 
 a fuel metering diaphragm defining part of the fuel metering chamber and having at least a portion that is movable relative to the body to increase and decrease the volume of the fuel metering chamber to control fuel flow in the fuel metering chamber, the fuel metering diaphragm also defining part of a metering reference chamber that is separate from the fuel metering chamber; and 
 a fluid pump carried by the carburetor or carried by another component upstream of the carburetor relative to the direction of air flow through the carburetor and having a pump chamber with an an outlet in fluid communication with the metering reference chamber and an actuator arranged to discharge air through the outlet to increase the air pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber into the air-fuel passage to provide a supplemental fuel supply to the engine. 
 
     
     
       2. The carburetor of  claim 1  wherein the body includes a pressure signal passage communicating an engine pressure signal with the actuator, and the actuator includes a pump diaphragm that defines part of the pump chamber and is displaced from a first position by the pressure signal to increase the volume of the pump chamber during at least one operating condition and to provide a volume of air to the metering reference chamber when the pump diaphragm returns toward its first position. 
     
     
       3. The carburetor of  claim 2  which also includes a vent in communication with the metering reference chamber and pump chamber. 
     
     
       4. The carburetor of  claim 1  which also includes a vent in communication with the metering reference chamber and pump chamber. 
     
     
       5. A carburetor that provides a supplemental fuel supply to an engine, comprising:
 a body having an air-fuel passage from which a fuel and air mixture flows from the carburetor, and a fuel metering chamber from which fuel flows to the air-fuel passage; 
 a fuel metering diaphragm defining part of the fuel metering chamber and having at least a portion that is movable relative to the body to increase and decrease the volume of the fuel metering chamber to control fuel flow in the fuel metering chamber, the fuel metering diaphragm also defining part of a metering reference chamber that is separate from the fuel metering chamber; 
 a fluid pump carried by the carburetor or carried by another component upstream of the carburetor relative to the direction of air flow through the carburetor and having an outlet in fluid communication with the metering reference chamber and an actuator arranged to discharge fluid through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage to provide a supplemental fuel supply to the engine; 
 a pressure signal passage in the body and communicating an engine pressure signal with the actuator, the actuator includes a pump diaphragm that defines part of a pump chamber and is displaced from a first position by the pressure signal to increase the volume of the pump chamber during at least one operating condition and to provide a volume of fluid to the metering reference chamber when the pump diaphragm returns toward its first position; 
 a biasing member that yieldably biases the pump diaphragm toward its first position and wherein the pressure signal passage provides a subatmospheric pressure signal to a side of the pump diaphragm opposite the pump chamber to increase the volume of the pump chamber at least at idle engine operation. 
 
     
     
       6. The carburetor of  claim 5  wherein the biasing member provides a force on the pump diaphragm that is greater than any subatmospheric pressure signal provided on the pump diaphragm through the pressure signal passage when the engine is operating at wide open throttle. 
     
     
       7. The carburetor of  claim 5  wherein the fluid pump is carried by a cover that defines part of the metering reference chamber. 
     
     
       8. A carburetor that provides a supplemental fuel supply to an engine, comprising:
 a body having an air-fuel passage from which a fuel and air mixture flows from the carburetor, and a fuel metering chamber from which fuel flows to the air-fuel passage; 
 a fuel metering diaphragm defining part of the fuel metering chamber and having at least a portion that is movable relative to the body to increase and decrease the volume of the fuel metering chamber to control fuel flow in the fuel metering chamber, the fuel metering diaphragm also defining part of a metering reference chamber that is separate from the fuel metering chamber; 
 a fluid pump carried by the carburetor or carried by another component upstream of the carburetor relative to the direction of air flow through the carburetor and having an outlet in fluid communication with the metering reference chamber and an actuator arranged to discharge fluid through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage to provide a supplemental fuel supply to the engine; 
 a pressure signal passage in the body and communicating an engine pressure signal with the actuator, and the actuator includes a pump diaphragm that defines part of a pump chamber and is displaced from a first position by the pressure signal to increase the volume of the pump chamber during at least one operating condition and to provide a volume of fluid to the metering reference chamber when the pump diaphragm returns toward its first position; and 
 a valve that selectively inhibits or prevents communication of the pressure signal with the pump diaphragm. 
 
     
     
       9. The carburetor of  claim 8  wherein the valve is mechanically actuated. 
     
     
       10. The carburetor of  claim 8  wherein the valve is electrically actuated. 
     
     
       11. A carburetor that provides a supplemental fuel supply to an engine, comprising:
 a body having an air-fuel passage from which a fuel and air mixture flows from the carburetor, and a fuel metering chamber from which fuel flows to the air-fuel passage; 
 a pressure signal passage through which an engine pressure signal source is routed; 
 a fuel metering diaphragm defining part of the fuel metering chamber, and defining part of a metering reference chamber that is separate from the fuel metering chamber, the fuel metering diaphragm having a portion that moves relative to the body; and 
 a pump diaphragm carried by the carburetor to define, with a portion of the carburetor body or another component of the carburetor, a pump chamber on one side of the pump diaphragm and a reference chamber on the opposite side of the pump diaphragm that is communicated with the pressure signal passage, wherein the pump chamber has an outlet that is in fluid communication with the metering reference chamber and the pump diaphragm is flexed in response to a pressure signal from the pressure signal passage to vary the volume of the pump chamber and selectively move air from the pump chamber through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage. 
 
     
     
       12. The carburetor of  claim 11  which also includes a vent in communication with the metering reference chamber and pump chamber. 
     
     
       13. A carburetor that provides a supplemental fuel supply to an engine, comprising:
 a body having an air-fuel passage from which a fuel and air mixture flows from the carburetor, and a fuel metering chamber from which fuel flows to the air-fuel passage; 
 a pressure signal passage through which an engine pressure signal source is routed; 
 a fuel metering diaphragm defining part of the fuel metering chamber, and defining part of a metering reference chamber that is separate from the fuel metering chamber, the fuel metering diaphragm having a portion that moves relative to the body; 
 a pump diaphragm carried by the carburetor to define, with a portion of the carburetor body or another component of the carburetor, a pump chamber on one side of the pump diaphragm and a reference chamber on the opposite side of the pump diaphragm that is communicated with the pressure signal passage, wherein the pump chamber has an outlet that is in fluid communication with the metering reference chamber and the pump diaphragm is flexed in response to a pressure signal from the pressure signal passage to vary the volume of the pump chamber and selectively move air from the pump chamber through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage; and 
 a biasing member that yieldably biases the pump diaphragm toward its first position and wherein the pressure signal passage provides a subatmospheric pressure signal to a side of the pump diaphragm opposite the pump chamber to increase the volume of the pump chamber at least at idle engine operation. 
 
     
     
       14. The carburetor of  claim 13  wherein the biasing member provides a force on the pump diaphragm that is greater than any subatmospheric pressure signal provided on the pump diaphragm through the pressure signal passage when the engine is operating at wide open throttle. 
     
     
       15. The carburetor of  claim 13  wherein the fluid pump is carried by a cover that defines part of the metering reference chamber. 
     
     
       16. The carburetor of  claim 13  which also includes a vent in communication with the metering reference chamber and pump chamber. 
     
     
       17. A carburetor that provides a supplemental fuel supply to an engine, comprising:
 a body having an air-fuel passage from which a fuel and air mixture flows from the carburetor, and a fuel metering chamber from which fuel flows to the air-fuel passage; 
 a pressure signal passage through which an engine pressure signal source is routed; 
 a fuel metering diaphragm defining part of the fuel metering chamber, and defining part of a metering reference chamber that is separate from the fuel metering chamber, the fuel metering diaphragm having a portion that moves relative to the body; 
 a pump diaphragm carried by the carburetor to define, with a portion of the carburetor body or another component of the carburetor, a pump chamber on one side of the pump diaphragm and a reference chamber on the opposite side of the pump diaphragm that is communicated with the pressure signal passage, wherein the pump chamber has an outlet that is in fluid communication with the metering reference chamber and the pump diaphragm is flexed in response to a pressure signal from the pressure signal passage to vary the volume of the pump chamber and selectively move air from the pump chamber through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage; and 
 a valve that selectively inhibits or prevents communication of the pressure signal with the actuator. 
 
     
     
       18. The carburetor of  claim 17  wherein the valve is mechanically actuated. 
     
     
       19. The carburetor of  claim 17  wherein the valve is electrically actuated.